1. Field of the Invention
The present invention relates to a transmitter, a receiver, a communication apparatus, and a communication method capable of executing a centralization process of digital data by concentrating the digital data, which being transmitted from a plurality of external devices which enable execution of data exchange at their natural transmission speeds respectively or being transmitted from an external network, to a common data transfer line, a common multiplexer, or a common distributor, and also capable of implementing smooth two-way communications between the external network and the plurality of external devices or between the plurality of external devices.
The present invention also relates to a communication system constructed by connecting a plurality of communication apparatuses via a data transmission line to execute data exchange between the plurality of communication apparatuses and, more particularly, a communication system capable of implementing smooth two-way communications between the plurality of communication apparatuses.
The present invention also relates to a communication system constructed by connecting a plurality of communication apparatuses, to which one external device or more than two external devices being connected respectively, via a data transmission line to execute data exchange between any external devices, between any communication apparatuses, or between any external device and any communication apparatus and, more particularly, a communication method and a communication system capable of improving a communication efficiency remarkably by avoiding surely collision between communication data.
2. Description of the Prior Art
As protocols for communication devices or apparatuses commonly used in the prior art, D2B (Audio, video and audiovisual systems Domestic Digital Bus: CIE/IEC 1030) employed to transmit digital audio data, etc.; standard which conforms to a recommendation made by CCITT (International Telegraph and Telephone Consulting Committee) and is used to execute personal computer communication, etc.; USB (Universal Serial Bus) and IEEE1394 used to connect personal computer peripheral devices such as a keyboard, a CRT display, a mouse, a modem, and a printer to a personal computer main body; ATAPI (AT Attachment Packet Interface) used as an interface to connect devices such as a DVD (Digital Video Disc or Digital Versatile Disc) -ROM drive, or a music CD (Compact Disc) player; MPEG2 (Moving Picture Image Coding Experts Group Phase2: ISO/IEC13818) which is a full color moving picture compression scheme for a digital TV set, etc.; ATM (Asynchronous Transfer Mode) for a computer and a digital TV set; and the like, for example, have been known.
In recent, there has been caused a request to implement a centralization process by concentrating sound data or video data supplied from various vehicle-equipped devices such as a radio, a mobile telephone, a TV set, a CD player, a navigation system; speed data supplied from a speed sensor; moving orientation data supplied from a geomagnetism sensor; data of running conditions of the vehicle such as the distance data between own vehicle and the next vehicle ahead running in the same direction, and the like. The reason for such centralization process is that, if such centralization process can be executed by concentrating output data supplied from various vehicle-equipped devices, various sensors, and forth arranged in various locations of the vehicle, mutual output data can be commonly used by respective vehicle-equipped devices, and simultaneously necessary data can be communicated at once when an vehicle-vehicle communication to execute data communication between own vehicle and another vehicle and a road-vehicle communication to execute data communication between own vehicle and stations arranged along the running route should be conducted, so that convenience of the vehicle can be improved.
With the above mentioned protocols, communication speeds, data formats, etc. have been specified individually according to respective protocols without regard to compatibility or interchangeability of communications in the existing circumstances. Accordingly, in the event that data communication should be executed between the vehicle-equipped devices which have mutually different protocols respectively, for example, in general personal computers in which an interface and a communication control unit both being constructed to enable communications between object protocols are built in previously have been connected to respective vehicle-equipped devices and then personal computer communications through such personal computers have been carried out.
However, in such data communications between the vehicle-equipped devices, there have been many limitations to construct a system, e.g., the personal computers have to be connected to respective vehicle-equipped devices. Such many limitations have made it difficult to improve flexibility of the system and have become obstacles to construction of the communication system such as the vehicle-vehicle communication or the road-vehicle communication for which the centralization process of data is requested.
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a transmitter, a receiver, a communication apparatus, and a communication method capable of executing a centralization process of digital data by concentrating the digital data, which being transmitted from a plurality of external devices which can execute data exchange at their natural transmission speeds respectively or being transmitted from an external network, to a common data transfer line, a common multiplexer, or a common distributor, and also capable of implementing smooth two-way communications between the external network and the plurality of external devices.
Further, it is another object of the present invention to provide a communication system capable of implementing smooth two-way communications between any communication apparatuses in the communication system which is constructed by connecting a plurality of communication apparatuses via a data transmission line.
Furthermore, it is still another object of the present invention to provide a communication method and a communication system capable of improving a communication efficiency remarkably by avoiding collision between communication data surely when data exchange are executed between any external devices, between any communication apparatuses, or between any external device and any communication apparatus in the communication system which is constructed by connecting a plurality of communication apparatuses, to which one external device or more than two external devices being connected respectively, via a data transmission line.
In order to achieve the above objects, there is provided a transmitter comprising a data transfer line for transferring digital data; a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively; a plurality of frequency modulators connected to the plurality of interfaces in one-by-one correspondence, for executing a frequency modulation to synchronize the digital data which have natural transmission speeds on respective interfaces with a predetermined system clock on the data transfer line, and then sending out the digital data which are subjected to the frequency modulation to the data transfer line respectively; a multiplexer for multiplexing the digital data which are transmitted from the plurality of frequency modulators via the data transfer line in synchronism with the predetermined system clock, and then transmitting multiplexed digital data to an external network; and a clock generator for generating reference clocks including the predetermined system clock, and then supplying the reference clocks to the plurality of frequency modulators and the multiplexer respectively.
According to the present invention, first, in a plurality of frequency modulators, the frequency modulation is executed to synchronize the digital data which have natural transmission speeds on respective interfaces with a predetermined system clock on the data transfer line, and then the frequency-modulated digital data are sent out to the data transfer line respectively. Then, the multiplexer multiplexes the digital data which are transmitted from the plurality of frequency modulators via the data transfer line in synchronism with the predetermined system clock, and then transmits the multiplexed digital data to the external network.
Therefore, a centralization process of digital data can be executed by concentrating the digital data, which being transmitted from a plurality of external devices which can execute data exchange at their natural transmission speeds respectively, onto the common data transfer line. The digital data can also be multiplexed and then the multiplexed digital data can be transmitted to the external network.
In order to achieve the above object, there is provided a receiver comprising a data transfer line for transferring digital data; a distributor for receiving multiplexed digital data transmitted from an external network, and then distributing the multiplexed digital data by inverse multiplexing in synchronism with a predetermined system clock on the data transfer line to send out to the data transfer line; a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively; a plurality of frequency demodulators for receiving digital data output from the distributor via the data transfer line, then executing a frequency demodulation to synchronize input data which have been synchronized with the predetermined system clock on the data transfer line with the natural transmission speeds on the plurality of interfaces respectively, and then sending out the digital data which are subjected to the frequency demodulation to the plurality of interfaces respectively; and a clock generator for generating reference clocks including the predetermined system clock, and then supplying the reference clocks to the distributor and the plurality of frequency demodulators respectively.
According to the present invention, first, in the distributor, multiplexed digital data transmitted from an external network are received, and then the multiplexed digital data are distributed by inverse multiplexing in synchronism with the predetermined system clock on the data transfer line to send out to the data transfer line. Then, the plurality of frequency demodulators receive the digital data output from the distributor via the data transfer line, then execute the frequency demodulation to synchronize input data which have been synchronized with the predetermined system clock on the data transfer line with the natural transmission speeds on the plurality of interfaces respectively, and then send out the digital data which are subjected to the frequency demodulation to the plurality of interfaces respectively. The plurality of external devices then receive the digital data via the plurality of interfaces.
Accordingly, since the multiplexed digital data transmitted from the external network are distributed to respective digital data by inverse multiplexing to send out to the data transfer line, the centralization process of digital data can be executed by concentrating the digital data, and also respective external devices can receive respective digital data by transforming the digital data into data formats having communication speeds peculiar to the plurality of interfaces.
In order to achieve the above object, there is provided a communication apparatus comprising a data transfer line for transferring digital data; a distributor for receiving multiplexed digital data transmitted from an external network, and then distributing the multiplexed digital data by inverse multiplexing in synchronism with a predetermined system clock on the data transfer line to send out to the data transfer line; a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively; a plurality of frequency modulators connected to the plurality of interfaces in one-by-one correspondence, for executing a frequency modulation to synchronize the digital data which have natural transmission speeds on respective interfaces with a predetermined system clock on the data transfer line, and then sending out the digital data which are subjected to the frequency modulation to the data transfer line respectively; a plurality of frequency demodulators for receiving the digital data output from the distributor via the data transfer line, then executing a frequency demodulation to synchronize input digital data which have been synchronized with the predetermined system clock on the data transfer line with the natural transmission speeds on the plurality of interfaces respectively, and then sending out the digital data which are subjected to the frequency demodulation to the plurality of interfaces respectively; a multiplexer for multiplexing the digital data which are transmitted from the plurality of frequency modulators via the data transfer line in synchronism with the predetermined system clock, and then transmitting multiplexed digital data to an external network; and a clock generator for generating reference clocks including the predetermined system clock, and then supplying the generated reference clocks to the distributor, the multiplexer, the plurality of frequency modulators, and the plurality of frequency demodulators respectively.
According to the present invention, when the digital data transmitted from the plurality of external devices respectively are transmitted to the external network via the data transfer line, in the plurality of frequency modulators, the frequency modulation is executed to synchronize the digital data which have natural transmission speeds on respective interfaces with the predetermined system clock on the data transfer line, and then the frequency-modulated digital data are sent out to the data transfer line respectively. Then, the multiplexer multiplexes the digital data which are transmitted via the data transfer line in synchronism with the predetermined system clock and then transmits the multiplexed digital data to the external network.
Meanwhile, when the multiplexed digital data transmitted from the external network are received by the plurality of external devices via the data transfer line respectively, in the distributor, the multiplexed digital data transmitted from the external network are received, and then the multiplexed digital data are distributed by inverse multiplexing in synchronism with the predetermined system clock on the data transfer line to send out to the data transfer line. Then, the plurality of frequency demodulators receive the digital data output from the distributor via the data transfer line, then execute the frequency demodulation to synchronize input digital data which have been synchronized with the predetermined system clock on the data transfer line with the natural transmission speeds on the plurality of interfaces respectively, and then sending out the frequency-demodulated digital data to the plurality of interfaces respectively. The digital data are then received by the plurality of external devices via the plurality of interfaces respectively.
Accordingly, the centralization process of digital data can be executed by concentrating the digital data which being transmitted from the plurality of external devices which can execute data exchange at their natural communication speeds or being transmitted from the external network, and also two-way communications between the external network and the plurality of external devices can be carried out smoothly.
In order to achieve the above object, there is provided a communication method for use in a communication system including a data transfer line for transferring digital data, and a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively, the communication method comprising the steps of: executing a frequency modulation to synchronize the digital data which are output from the plurality of external devices having natural transmission speeds on the plurality of interfaces respectively with a predetermined system clock on the data transfer line, and then sending out the digital data which are subjected to the frequency modulation to the data transfer line respectively; and multiplexing the digital data which are input via the data transfer line respectively in synchronism with the predetermined system clock, and then transmitting multiplexed digital data to an external network; whereby the digital data transmitted from the plurality of external devices respectively are sent to the external network via the data transfer line, and receiving multiplexed digital data transmitted from the external network, and then distributing the multiplexed digital data by inverse multiplexing in synchronism with the predetermined system clock to send out to the data transfer line; receiving the digital data transmitted via the data transfer line respectively, and then executing a frequency demodulation to synchronize the digital data which have been synchronized with the predetermined system clock with the natural transmission speeds on the plurality of interfaces respectively; and receiving the digital data which are subjected to the frequency demodulation by the plurality of external devices via the plurality of interfaces respectively; whereby the multiplexed digital data transmitted from the external network are received by the plurality of external devices via the data transfer line respectively.
According to the present invention, when the digital data transmitted from the plurality of external devices respectively are sent to the external network via the data transfer line, the frequency modulation is executed to synchronize the digital data which are output from the plurality of external devices having their natural transmission speeds on the plurality of interfaces respectively with the predetermined system clock on the data transfer line, then the frequency-modulated digital data are sent out to the data transfer line respectively, then the digital data input via the data transfer line respectively are multiplexed in synchronism with the predetermined system clock, and then the multiplexed digital data are transmitted to the external network. Meanwhile, when the multiplexed digital data transmitted from the external network are received by the plurality of external devices via the data transfer line respectively, the multiplexed digital data are distributed by inverse multiplexing in synchronism with the predetermined system clock to send out to the data transfer line, then the digital data transmitted via the data transfer line respectively are received, then the frequency demodulation is executed to synchronize the digital data which have been synchronized with the predetermined system clock with the natural transmission speeds on the plurality of interfaces respectively, and then the digital data which are subjected to the frequency demodulation are received by the plurality of external devices via the plurality of interfaces respectively.
Accordingly, like the above communication apparatus, the centralization process of digital data can be executed by concentrating the digital data which being transmitted from the plurality of external devices which can execute data exchange at their natural communication speeds or being transmitted from the external network, and also two-way communications between the external network and the plurality of external devices can be carried out smoothly.
In the preferred embodiment of the present invention, the digital data input via the data transfer line respectively are transformed into plural packets and then transmitted to the external network on a time-division multiplex basis.
In the preferred embodiment of the present invention, the transmitter further comprises a plurality of information adding means for adding header information including at least destination to the digital data which are divided into a predetermined proper unit with respect to the plurality of interfaces and then output.
According to this embodiment, the digital data can be firmly transmitted to the predetermined sender by referring to header information added by the information adding means.
In the preferred embodiment of the present invention, the receiver further comprises a plurality of header information deleting means for deleting header information from the digital data to which the header information including at least destination are added and which are sent out from the distributor via the data transfer line.
According to this embodiment, the plurality of external devices can receive raw data without including the extra information respectively by deleting header information by the header information deleting means.
In the preferred embodiment of the present invention, the communication apparatus further comprises a plurality of information adding means for adding header information including at least destination to the digital data which are divided into a predetermined proper unit with respect to the plurality of interfaces and then output; and a plurality of header information deleting means for deleting the header information from the digital data to which the header information including at least destination are added and which are sent out from the distributor via the data transfer line.
According to this embodiment, the digital data can be firmly transmitted to the predetermined sender by referring to header information added by the information adding means, and the plurality of external devices can receive raw data without including the extra information respectively by deleting header information by the header information deleting means.
In the preferred embodiment of the present invention, data exchanges are executed between senders and destinations based on device reference clocks peculiar to the plurality of external devices which are distributed at predetermined distribution ratios of the predetermined system clock.
According to this embodiment, since data exchange can be executed between the senders and the destinations based on the device reference clocks peculiar to the plurality of external devices which are distributed at the predetermined distribution ratios of the predetermined system clock, smooth two-way communications can be implemented between the external network and the plurality of external devices.
In order to achieve the above object, there is provided a transmitter comprising a data transfer line for transferring digital data; a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively; a plurality of frequency modulators connected to the plurality of external interfaces in one-by-one correspondence, for executing a frequency modulation to synchronize the digital data which have natural transmission speeds on respective interfaces with a predetermined system clock of multiplexer side, and then sending out the digital data which are subjected to the frequency modulation to the data transfer line respectively; a multiplexer for multiplexing the digital data which are transmitted from the plurality of frequency modulators via the data transfer line in synchronism with the predetermined system clock of multiplexer side, and then transmitting multiplexed digital data to an external network; and a clock generator for generating reference clocks including the predetermined system clock and then supplying the generated reference clocks to the plurality of frequency modulators and the multiplexer respectively.
According to the present invention, first, in the plurality of frequency modulators, the frequency modulation is executed to synchronize the digital data which are output from the plurality of external devices having their natural transmission speeds on the plurality of interfaces respectively with the predetermined system clock of multiplexer side on the data transfer line, then the frequency-modulated digital data are sent out to the data transfer line respectively. Then, the multiplexer multiplexes the digital data input via the data transfer line respectively in synchronism with the predetermined system clock of multiplexer side, and then transmits the multiplexed digital data to the external network.
Accordingly, the centralization process of digital data can be executed by concentrating the digital data which being transmitted from the plurality of external devices which can execute data exchange at their natural communication speeds onto the multiplexer, and also the digital data multiplexed by the multiplexer can be transmitted to the external network.
In order to achieve the above object, there is provided a receiver comprising a data transfer line for transferring digital data; a distributor for receiving multiplexed digital data transmitted from an external network, and then distributing the multiplexed digital data by inverse multiplexing in synchronism with a predetermined system clock of distributor side in the data transfer line to send out to the data transfer line; a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively; a plurality of frequency demodulators for receiving the digital data output from the distributor via the data transfer line, then executing a frequency demodulation to synchronize the digital data which have been synchronized with the predetermined system clock of distributor side with the natural transmission speeds on the plurality of interfaces respectively, and then sending out the digital data which are subjected to the frequency demodulation to the plurality of interfaces respectively; and a clock generator for generating reference clocks including the predetermined system clock of distributor side, and then supplying the reference clocks to the distributor and the plurality of frequency demodulators respectively.
According to the present invention, the distributor receives the multiplexed digital data transmitted from the external network, and then distributes the multiplexed digital data by inverse multiplexing in synchronism with the predetermined system clock on the data transfer line to send out to the data transfer line. Then, the plurality of frequency demodulators execute the frequency demodulation to synchronize input digital data which have been synchronized with the predetermined system clock of distributor side with the natural transmission speeds on the plurality of interfaces respectively, and then sends out the frequency-demodulated digital data to the plurality of interfaces respectively. The digital data are then received by the plurality of external devices via the plurality of interfaces respectively.
Accordingly, the centralization process of digital data can be executed by concentrating the multiplexed digital data which being transmitted from the external network onto the distributor, and also the digital data distributed by the distributor can be transformed into data formats having the communication speeds peculiar to the plurality of interfaces to enable reception by the external devices respectively.
In order to achieve the above object, there is provided a communication apparatus comprising a data transfer line for transferring digital data; a distributor for receiving multiplexed data transmitted from an external network, and then distributing multiplexed digital data by inverse multiplexing in synchronism with a predetermined system clock of distributor side to send out to the data transfer line; a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively; a plurality of frequency modulators connected to the plurality of interfaces in one-by-one correspondence, for executing a frequency modulation to synchronize the digital data which have natural transmission speeds on respective interfaces with a predetermined system clock of multiplexer side, and then sending out the digital data which are subjected to the frequency modulation to the data transfer line respectively; a plurality of frequency demodulators for receiving the digital data which are output from the distributor via the data transfer line, then executing a frequency demodulation to synchronize the digital data which have been synchronized with the predetermined system clock of distributor side with the natural transmission speeds on the plurality of interfaces respectively, and then sending out the digital data which are subjected to the frequency demodulation to the plurality of interfaces respectively; a multiplexer for multiplexing the digital data which are transmitted from the plurality of frequency modulators via the data transfer line in synchronism with the predetermined system clock of multiplexer side, and then transmitting multiplexed digital data to an external network; and a clock generator for generating reference clocks including the predetermined system clock of distributor side and the predetermined system clock of multiplexer side, and then supplying the reference clocks to the distributor, the multiplexer, the plurality of frequency modulators, and the plurality of frequency demodulators respectively.
According to the present invention, when the digital data transmitted from the plurality of external devices respectively are transmitted to the external network via the data transfer line, in the plurality of frequency modulators, the frequency modulation is executed to synchronize the digital data which have natural transmission speeds on respective interfaces with the predetermined system clock on the data transfer line, and then the frequency-modulated digital data are sent out to the data transfer line respectively. Then, the multiplexer multiplexes the digital data which are transmitted via the data transfer line in synchronism with the predetermined system clock and then transmits the multiplexed digital data to the external network.
Meanwhile, when the multiplexed digital data transmitted from the external network are received by the plurality of external devices via the data transfer line respectively, in the distributor, the multiplexed digital data transmitted from the external network are received, and then the multiplexed digital data are distributed by inverse multiplexing in synchronism with the predetermined system clock on the data transfer line to send out to the data transfer line. Then, the plurality of frequency demodulators receive the digital data output from the distributor via the data transfer line, then execute the frequency demodulation to synchronize input digital data which have been synchronized with the predetermined system clock on the data transfer line with the natural transmission speeds on the plurality of interfaces respectively, and then sending out the frequency-demodulated digital data to the plurality of interfaces respectively. The digital data are then received by the plurality of external devices via the plurality of interfaces respectively.
Accordingly, the centralization process of digital data can be executed by concentrating the digital data, which being transmitted from the plurality of external devices which can execute data exchange at their natural communication speeds or being transmitted from the external network, onto the multiplexer or the distributor, and also the two-way communications between the external network and the plurality of external devices can be carried out smoothly.
In order to achieve the above object, there is provided a communication method for use in a communication system including, a data transfer line for transferring digital data, and a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively, the communication method comprising the steps of: executing a frequency modulation to synchronize the digital data which are output from the plurality of external devices having the natural transmission speeds on the plurality of interfaces respectively with a predetermined system clock of multiplexer side, and then sending out the digital data which are subjected to the frequency modulation to the data transfer line respectively; and multiplexing the digital data which are input via the data transfer line respectively in synchronism with the predetermined system clock of multiplexer side, and then transmitting multiplexed digital data to an external network; whereby the digital data which are transmitted from the plurality of external devices respectively are sent to the external network via the data transfer line, and receiving the multiplexed digital data transmitted from the external network, and then distributing the multiplexed digital data by inverse multiplexing in synchronism with the predetermined system clock of distributor side to send out to the data transfer line; receiving the digital data transmitted via the data transfer line respectively, and then executing a frequency demodulation to synchronize the digital data which have been synchronized with the predetermined system clock of distributor side with the natural transmission speeds on the plurality of interfaces respectively; and receiving the digital data which are subjected to the frequency demodulation by the plurality of external devices via the plurality of interfaces respectively; whereby the multiplexed digital data which are transmitted from the external network are received by the plurality of external devices via the data transfer line respectively.
According to the present invention, when the digital data transmitted from the plurality of external devices respectively are transmitted to the external network via the data transfer line, the frequency modulation is executed to synchronize the digital data which are output from the plurality of external devices having their natural transmission speeds on the plurality of interfaces respectively with the predetermined system clock of multiplexer side, and then the frequency-modulated digital data are sent out to the data transfer line respectively. Then, the digital data which are transmitted via the data transfer line respectively are multiplexed in synchronism with the predetermined system clock of multiplexer side and then the multiplexed digital data are transmitted to the external network. Meanwhile, when the multiplexed digital data transmitted from the external network are received by the plurality of external devices via the data transfer line respectively, the multiplexed digital data transmitted from the external network are received, and then the multiplexed digital data are distributed by inverse multiplexing in synchronism with the predetermined system clock of distributor side to send out to the data transfer line. Then, the frequency demodulation is executed to synchronize input digital data which have been synchronized with the predetermined system clock of distributor side with the transmission speeds peculiar to the plurality of interfaces respectively, and then the frequency-demodulated digital data are received by the plurality of external devices via the plurality of interfaces respectively.
Accordingly, the centralization process of digital data can be executed by concentrating the digital data, which being transmitted from the plurality of external devices which can execute data exchange at their natural communication speeds or being transmitted from the external network, onto the multiplexing or distributing function portion, and also the two-way communications between the external network and the plurality of external devices can be carried out smoothly.
In the preferred embodiment of the present invention, the digital data which are input via the data transfer line respectively are transformed into plural packets and then transmitted to the external network on a time-division multiplex basis.
In the preferred embodiment of the present invention, data exchanges are executed between senders and destinations based on device reference clocks peculiar to the plurality of external devices which are distributed at predetermined distribution ratios of the predetermined system clock.
According to this embodiment, since data exchange can be executed between the senders and the destinations based on the device reference clocks peculiar to the plurality of external devices which are distributed at the predetermined distribution ratios of the predetermined system clock, smooth two-way communications can be implemented between the external network and the plurality of external devices.
In the preferred embodiment of the present invention, the multiplexer side system clock and the distributor side system clock are set mutually at a common frequency.
In the preferred embodiment of the present invention, the transmitter further comprises a plurality of information adding means for adding header information including at least destination to the digital data which are divided into a predetermined proper unit with respect to the plurality of interfaces and then output.
According to this embodiment, the digital data can be firmly transmitted to the predetermined sender by referring to header information added by the information adding means.
In the preferred embodiment of the present invention, the receiver further comprises a plurality of header information deleting means for deleting header information from the digital data to which the header information including at least destination are added and which are sent out from the distributor via the data transfer line.
According to this embodiment, the plurality of external devices can receive raw data without including the extra information respectively by deleting header information by the header information deleting means.
In the preferred embodiment of the present invention, the communication apparatus further comprises a plurality of information adding means for adding header information including at least destination to the digital data which are divided into a predetermined proper unit with respect to the plurality of interfaces and then output; and a plurality of header information deleting means for deleting the header information from the digital data to which the header information including at least the destination are added and which are sent out from the distributor via the data transfer line.
According to this embodiment, the digital data can be firmly transmitted to the predetermined sender by referring to header information added by the information adding means, and the plurality of external devices can receive raw data without including the extra information respectively by deleting header information by the header information deleting means.
In order to achieve the above object, there is provided a communication method for use in a communication system including a data transfer line for transferring digital data, and a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively, the communication method comprising the steps of: adding header information including at least destination to the digital data which have natural communication speeds on the plurality of interfaces and are divided into a predetermined proper unit of the plurality of interfaces and then output; executing a frequency modulation to synchronize the digital data to which the header information are added with a predetermined system clock of multiplexer side, and then sending out the digital data which are subjected to the frequency modulation to the data transfer line respectively; and multiplexing the digital data which are input via the data transfer line respectively in synchronism with the predetermined system clock of multiplexer side, and then transmitting multiplexed digital data to an external network; whereby the digital data which are transmitted from the plurality of external devices respectively are sent to the external network via the data transfer line, and receiving the multiplexed digital data transmitted from the external network, and then distributing the multiplexed digital data by inverse multiplexing in synchronism with a predetermined system clock of distributor side to send out to the data transfer line; receiving the digital data which are transmitted via the data transfer line respectively, and then executing a frequency demodulation to synchronize the digital data which have been synchronized with the predetermined system clock of distributor side with the natural transmission speeds on the plurality of interfaces respectively; and receiving the digital data which are subjected to the frequency demodulation by the plurality of external devices via the plurality of interfaces respectively; whereby the multiplexed digital data which are transmitted from the external network are received by the plurality of external devices via the data transfer line respectively.
According to the present invention, when the digital data transmitted from the plurality of external devices respectively are transmitted to the external network via the data transfer line, header information including at least destination are added respectively to the digital data which have their natural communication speeds on the plurality of interfaces and are divided into predetermined proper units on the plurality of interfaces respectively and then output, then the frequency modulation is executed to synchronize the digital data to which the header information are added respectively with the predetermined system clock of multiplexer side, and then the frequency-modulated digital data are sent out to the data transfer line respectively. Then, the digital data which are transmitted via the data transfer line respectively are multiplexed in synchronism with the predetermined system clock of multiplexer side and then the multiplexed digital data are transmitted to the external network.
In order to achieve the above object, there is provided a communication method for use in a communication system including a data transfer line for transferring digital data, and a plurality of interfaces connected to a plurality of external devices in one-by-one correspondence, and constructed so as to fit to transmission speeds peculiar to the plurality of external devices respectively, the communication method comprising the steps of: executing a frequency modulation to synchronize the digital data which have natural communication speeds on the plurality of interfaces with a predetermined system clock of multiplexer side; adding header information including at least destination to the digital data which are subjected to the frequency modulation and are divided into a predetermined proper unit of the plurality of interfaces and then output respectively, and then sending out the digital data to which the header information are added to the data transfer line respectively; and multiplexing the digital data which are input via the data transfer line respectively in synchronism with the predetermined system clock of multiplexer side, and then transmitting multiplexed digital data to an external network; whereby the digital data which are transmitted from the plurality of external devices respectively are sent to the external network via the data transfer line, and receiving the multiplexed digital data transmitted from the external network, and then distributing the multiplexed digital data by inverse multiplexing in synchronism with a predetermined system clock of distributor side to send out to the data transfer line; receiving the digital data which are transmitted via the data transfer line respectively, and then executing a frequency demodulation to synchronize the digital data which have been synchronized with the predetermined system clock of distributor side with the natural transmission speeds on the plurality of interfaces respectively; and receiving the digital data which are subjected to the frequency demodulation by the plurality of external devices via the plurality of interfaces respectively; whereby the multiplexed digital data which are transmitted from the external network are received by the plurality of external devices via the data transfer line respectively.
According to the present invention, when the digital data transmitted from the plurality of external devices respectively are transmitted to the external network via the data transfer line, the frequency modulation is executed to synchronize the digital data which have their natural transmission speeds on the plurality of interfaces respectively with the predetermined system clock of multiplexer side, then the header information including at least destination are added respectively to the digital data which have been subjected to the frequency modulation and divided into predetermined proper units on the plurality of interfaces and then output respectively, and then the digital data to which the header information are added are sent out to the data transfer line respectively. Then, the digital data which are received via the data transfer line respectively are multiplexed in synchronism with the predetermined system clock of multiplexer side and then the multiplexed digital data are transmitted to the external network.
In order to achieve the above object, there is provided, in a communication system constructed by connecting a plurality of communication apparatuses via a data transmission line to execute data exchange between any communication apparatuses, the plurality of communication apparatuses are constructed so as to access the data transmission line at timing periods peculiar to respective communication apparatuses in synchronism with a common system clock among respective communication apparatuses, and the timing periods peculiar to respective communication apparatuses are set to be shifted mutually such that accesses to the data transmission line are not simultaneously generated from the plurality of communication apparatuses.
According to the present invention, the plurality of communication apparatuses are constructed so as to access the data transmission line at their timing periods peculiar to respective communication apparatuses in synchronism with the common system clock among the plurality of communication apparatuses and also the timing periods peculiar to respective communication apparatuses are set to be shifted mutually such that access to the data transmission line are not simultaneously generated from the plurality of communication apparatuses. Therefore, the plurality of communication apparatuses can access the data transmission line in parallel respectively with avoiding collision of data. As a result, smooth two-way communications between any communication apparatuses can be realized while assuring excellent real-time facility.
In order to achieve the above object, there is provided, in a communication system constructed by connecting a plurality of communication apparatuses via a star-configuration data transmission line which is arranged around one centralized controller to execute data exchange between any communication apparatuses, the plurality of communication apparatuses are constructed so as to access the centralized controller at timing periods peculiar to respective communication apparatuses in synchronism with a common system clock among respective communication apparatuses, and the timing periods peculiar to the communication apparatuses are set to be shifted mutually such that accesses to the centralized controller are not simultaneously generated from the plurality of communication apparatuses.
According to the present invention, the plurality of communication apparatuses are constructed so as to access the centralized controller at their timing periods peculiar to respective communication apparatuses in synchronism with the common system clock among the plurality of communication apparatuses and in addition the timing periods peculiar to respective communication apparatuses are set to be shifted mutually such that access to the centralized controller are not simultaneously generated from the plurality of communication apparatuses. Hence, the plurality of communication apparatuses can access the centralized controller in parallel respectively with avoiding collision of data. As a result, smooth two-way communications between any communication apparatuses and the centralized controller can be realized while assuring excellent real-time facility and in addition the communication system having a simple configuration to which the centralized controller and the buffer memory for storing overflow data temporarily are not required can be achieved.
In order to achieve the above object, there is provided, in a communication method for use in a communication system which is constructed by connecting a plurality of communication apparatuses via a data transmission line to execute data exchange between any communication apparatuses, the plurality of communication apparatuses are constructed so as to access the data transmission line in synchronism with predetermined timing clocks which are set to respective communication apparatuses in synchronism with a common system clock among respective communication apparatuses, when data exchange is executed between a sender communication apparatus and a destination communication apparatus among the plurality of communication apparatuses, communication channels can be established by producing the predetermined timing clocks which are commonly used between the sender communication apparatus and the destination communication apparatus, the sender communication apparatus can execute data transmission in synchronism with the predetermined timing clock, and
the destination communication apparatus can receive data in synchronism with the predetermined timing clock.
According to the present invention, when data exchange is to be executed between the sender communication apparatus and the destination communication apparatus, first of all, a communication route is generated by establishing a predetermined timing clock used commonly between both communication apparatuses, then the sender communication apparatus executes data transmission in synchronism with a predetermined timing clock while the destination communication apparatus executes data reception in synchronism with the predetermined timing clock. Accordingly, the plurality of communication apparatuses can access the data transmission lines in parallel respectively with avoiding collision of data. As a result, smooth two-way communications between any communication apparatuses can be realized while assuring excellent real-time facility.
In order to achieve the above object, there is provided, in a communication method for use in a communication system which is constructed by connecting a plurality of communication apparatuses, to which one external device or two or more external devices are connected respectively, via a data transmission line to execute data exchange between any external devices, between any communication apparatuses, or between any external device and any communication apparatus, at least one of communication apparatuses out of the plurality of communication apparatuses can generate clock allocation information in connection with distribution ratios of a common system clock among the plurality of communication apparatuses to various external devices respectively based on all device connection information including type of the external devices connected to the plurality of communication apparatuses constituting the communication system, and can transmit the clock allocation information to overall communication apparatuses including its own communication apparatus, the plurality of communication apparatuses including the at least of communication apparatus execute data can exchange between any sender and any destination based on device reference clocks peculiar to various external devices and distributed at distribution ratios of the system clock according to the clock allocation information, and a plurality of device reference clocks peculiar to the various external devices are set such that respective rising times of their pulses are shifted mutually with regard to a fact that pulse rising timings as data communication timings of the various external devices are not generated simultaneously between the external devices.
According to the present invention, at least one of the communication apparatuses out of the plurality of communication apparatuses generates the clock allocation information concerning the distribution ratios of the system clock common to the plurality of communication apparatuses for respective external devices based on the all device connection information, and transmits the generated clock allocation information to all communication apparatuses including own communication apparatus. In response to the clock allocation information, the plurality of communication apparatuses including own communication apparatus execute data exchange between any sender and any destination based on the device reference clocks which are distributed at distribution ratios of the system clock in compliance with the clock allocation information and peculiar to various external devices.
In this manner, communication data transmitted from various external devices are transmitted to the data transmission line respectively in synchronism with the communication timings in compliance with the device reference clocks peculiar to respective external devices and also pulse rising timings which serve as the communication timings for the communication data being transmitted from various external devices respectively are set to be shifted mutually. Therefore, plural communication data can be prevented beforehand from being transmitted simultaneously from different senders and thus collision of the communication data can be avoided firmly. As a result, the communication apparatus which is able to improve communication efficiency remarkably can be realized.
In order to achieve the above object, there is provided, in a communication method for use in a communication system which is constructed by connecting a plurality of communication apparatuses, to which one external device or two or more external devices are connected respectively, via a data transmission line to execute data exchange between any external devices, between any communication apparatuses, or between any external device and any communication apparatus, at least one of communication apparatuses out of the plurality of communication apparatuses can generate clock allocation information assigned to various external devices respectively in connection with distribution ratios of a common system clock among the plurality of communication apparatuses based on all device connection information including type of the external devices which are connected to the plurality of communication apparatuses constituting the communication system, and can transmit the clock allocation information to overall communication apparatuses including its own communication apparatus, the plurality of communication apparatuses including the at least of communication apparatus execute data can exchange between any sender and any destination based on device reference clocks peculiar to various external devices and distributed at distribution ratios of the system clock according to the clock allocation information, and a plurality of device reference clocks peculiar to the various external devices are set such that respective trailing times of their pulses are shifted mutually with regard to a fact that pulse trailing timings as data communication timings of the various external devices are not generated simultaneously between the external devices.
According to the present invention, at least one of the communication apparatuses out of the plurality of communication apparatuses generates the clock allocation information concerning the distribution ratios of the system clock common to the plurality of communication apparatuses for respective external devices based on the all device connection information, and transmits the generated clock allocation information to all communication apparatuses including own communication apparatus. In response to the clock allocation information, the plurality of communication apparatuses including own communication apparatus execute data exchange between any sender and any destination based on the device reference clocks which are distributed at distribution ratios of the system clock in compliance with the clock allocation information and peculiar to various external devices.
Like this, communication data transmitted from various external devices are transmitted to the data transmission line respectively in synchronism with the communication timings in compliance with the device reference clocks peculiar to respective external devices and also pulse rising timings which serve as the communication timings for the communication data being transmitted from various external devices respectively are set to be shifted mutually. Therefore, plural communication data can be prevented beforehand from being transmitted simultaneously from different senders and thus collision of the communication data can be avoided firmly. As a result, the communication apparatus which is able to improve communication efficiency remarkably can be realized.
In order to achieve the above object, there is provided, in a communication system which is constructed by connecting a plurality of communication apparatuses, to which one external device or two or more external devices are connected respectively, via a data transmission line to execute data exchange between any external devices, between any communication apparatuses, or between any external device and any communication apparatus, at least one of communication apparatuses out of the plurality of communication apparatuses comprising: an all device connection information storing means for storing all device connection information including type of the external devices which are connected respectively to the plurality of communication apparatuses constituting the communication system; a clock allocating means for generating clock allocation information concerning distribution ratios of a system clock which is common among the plurality of communication apparatuses for respective external devices, based on the all device connection information stored in the all device connection information storing means; and a clock allocation information transmitting means for transmitting the clock allocation information generated by the clock allocating means to all communication apparatuses including own communication apparatus; and the plurality of communication apparatuses including the at least one of communication apparatus comprising: a clock allocation information receiving means for receiving the clock allocation information transmitted from the clock allocation information transmitting means; and a data exchange controlling means for controlling data exchange between any sender and any destination, based on device reference clocks peculiar to respective external devices which are distributed at the distribution ratios of the system clock according to the clock allocation information received by the clock allocation information receiving means; wherein the plurality of device reference clocks peculiar to the various external devices respectively are set such that respective rising times of their pulses are shifted mutually with regard to a fact that pulse rising timings as data communication timings of the various external devices are not simultaneously generated mutually between the external devices.
According to the present invention, in at least one of communication apparatuses out of the plurality of communication apparatuses, the clock allocating means generates clock allocation information concerning distribution ratios of the system clock which is common among the plurality of communication apparatuses for respective external devices, based on all device connection information stored in all device connection information storing means, and the clock allocation information transmitting means transmits the clock allocation information generated by the clock allocating means to all communication apparatuses including own communication apparatus.
On the contrary, in the plurality of communication apparatuses including at least one of communication apparatuses, the clock allocation information receiving means receives the clock allocation information transmitted from the clock allocation information transmitting means, and the data exchange controlling means controls data exchange between any sender and any destination, based on device reference clocks which are peculiar to respective external devices and are distributed at the distribution ratios of the system clock according to the clock allocation information received by the clock allocation information receiving means.
In this fashion, communication data transmitted from various external devices are transmitted to the data transmission line respectively in synchronism with the communication timings in compliance with the device reference clocks peculiar to respective external devices and also pulse rising timings which serve as the communication timings for the communication data being transmitted from various external devices respectively are set to be shifted mutually. Therefore, plural communication data can be prevented beforehand from being transmitted simultaneously from different senders and thus collision of the communication data can be avoided firmly. As a result, the communication apparatus which is able to improve communication efficiency remarkably can be realized.
In the preferred embodiment of the present invention, the plurality of device reference clocks peculiar to the various external devices include a command dedicated clock for transmitting a command.
According to this embodiment, since the plurality of device reference clocks peculiar to various external devices are constructed to include the command dedicated clock for command transmission, the communication system which is able to transmit the command from the sender to the destination with a simple configuration can be implemented.
In order to achieve the above object, there is provided, in a communication system which is constructed by connecting a plurality of communication apparatuses, to which one external device or two or more external devices are connected respectively, via a data transmission line to execute data exchange between any external devices, between any communication apparatuses, or between any external device and any communication apparatus, at least one of communication apparatuses out of the plurality of communication apparatuses comprising: an all device connection information storing means for storing all device connection information including type of the external devices which are connected respectively to the plurality of communication apparatuses constituting the communication system; a clock allocating means for generating clock allocation information concerning distribution ratios of a system clock which is common among the plurality of communication apparatuses for respective external devices, based on the all device connection information stored in the all device connection information storing means; and a clock allocation information transmitting means for transmitting the clock allocation information generated by the clock allocating means to all communication apparatuses including own communication apparatus; and the plurality of communication apparatuses including the at least one of communication apparatus comprising: a clock allocation information receiving means for receiving the clock allocation information transmitted from the clock allocation information transmitting means; and a data exchange controlling means for controlling data exchange between any sender and any destination, based on device reference clocks peculiar to respective external devices which are distributed at the distribution ratios of the system clock according to the clock allocation information received by the clock allocation information receiving means; wherein the plurality of device reference clocks peculiar to the various external devices respectively are set such that respective trailing times of their pulses are shifted mutually with regard to a fact that pulse trailing timings as data communication timings of the various external devices are not simultaneously generated mutually between the external devices.
According to the present invention, in at least one of communication apparatuses out of the plurality of communication apparatuses, the clock allocating means generates clock allocation information concerning distribution ratios of the system clock which is common among the plurality of communication apparatuses for respective external devices, based on all device connection information stored in all device connection information storing means, and the clock allocation information transmitting means transmits the clock allocation information generated by the clock allocating means to all communication apparatuses including own communication apparatus.
While, in the plurality of communication apparatuses including at least one of communication apparatuses, the clock allocation information receiving means receives the clock allocation information transmitted from the clock allocation information transmitting means, and the data exchange controlling means controls data exchange between any sender and any destination, based on device reference clocks which are peculiar to respective external devices and are distributed at the distribution ratios of the system clock according to the clock allocation information received by the clock allocation information receiving means.
In this manner, communication data transmitted from various external devices are transmitted to the data transmission line respectively in synchronism with the communication timings in compliance with the device reference clocks peculiar to respective external devices and also pulse rising timings which serve as the communication timings for the communication data being transmitted from various external devices respectively are set to be shifted mutually. Therefore, plural communication data can be prevented beforehand from being transmitted simultaneously from different senders and thus collision of the communication data can be avoided firmly. As a result, the communication apparatus which is able to improve communication efficiency remarkably can be realized.
In the preferred embodiment of the present invention, the plurality of device reference clocks peculiar to the various external devices include a command dedicated clock for transmitting a command.
According to this embodiment, since the plurality of device reference clocks peculiar to various external devices are constructed to include the command dedicated clock for command transmission, the communication system which is able to transmit the command from the sender to the destination with a simple configuration can be implemented.